a = 1
while a <= 100:
    print('今天是第%d天' % a)
    a = a + 1


n = 1
sum = 0
while n <= 100:
    sum =sum+n
    n = n+ 1
    # print(sum)
print(sum)


for i in 'python':
    print(i)
    for i in range(9):
        print(i)
        # 单分支if语句
# 函数的功能:将字符串str当成有效的表达式来求值并返回计算结果
score = eval(input('请输入成绩分数'))
if score >=60:
    print("成绩已合格")
# 分别输入58 75 87 100进行测试 60 80 90 100
score = eval(input('请输入成绩分数'))
if score < 60:
    print("成绩不合格")
if 60 <= score < 80:
    print("成绩一般")
if 80 <= score <= 90:
    print("成绩良好")
if 90 < score <= 100:
    print("成绩优秀")
# 嵌套if分别输入88 99进行测试
score = eval(input('请输入成绩分数'))
if 60 <= score:
    print("成绩已合格")
    if 90 < score <= 100:
        print("成绩优秀")